Yamaha 130HP idle issues - The Hull Truth

tommat · 04-27-2008, 02:13 PM

Hi, My engine has sit for about 6 months and though it started quickly this weekend but was idling rough and would stall. I replaced the plugs and same problem. I drained the bowels and flushed the openings. I removed the needle valves and cleaned the openings. After putting it all back together the fuel line bulb will not get hard. It seems like there is an air leak someplace as the internal fuel filter does not fill entirely up with fuel. All the fuel lines and bulb are new. Any thoughts as I can't understand how what I did would lead to this issue.

Thanks..

A1 Outboard · 04-27-2008, 08:15 PM

Without soaking the carb and checking every passageway and the float level, perhaps there is still some varnish or trash inside the carbs.

Check the fuel pump diaphragm for leakage as that will keep the primer ball from building up pressure and it will also flood the pulse cylinder which gives a poor idle.

Sqeeze off a section of fuel line above the primer ball and see if it will now get hard. If not, a bad ball, air leak, fuel filter seal or rust, etc. is keeping the pressure from building up.

tommat · 06-15-2008, 07:32 PM

Hi,

Here is what I have done so far. I removed the fuel line at the "T" connector right after the fuel pump and had pressure in the ball, so I knew that the carbs were somehow at fault. I then added fuel to the lower carb bowel through it's fuel line since all this started after I had drained them and cleaned the needle valves. I removed the top carb and then it's bowel. On the top of one of the pilot air jet's was build up that looked like pollen. Best way I can describe it. I cleaned it, added fresh fuel to the bowel and reassembled. The engine started, ran rough for a very short while and then died. The ball would not build up pressure after that. So does this mean that the carbs are still at fault or that the fuel pump is somehow not working correctly at adding fuel to the carbs when it does run? The carb that I removed looked pretty darn clean surprisingly as it's a 1992 and has never been rebuilt. The floats seemed ok, not that I have much experience with them

Thanks for your help and I look forward to your reply..

A1 Outboard · 06-16-2008, 09:16 PM

If the ball won't build up pressure, check or replace the ball with a factory one, not a Tempo or Atwood brand. Also check the fuel pump diaphragms for leaking fuel into the crankcase, and check for a flooding carb. You should still get a manual , factory carb kits, and clean them thoroughly by soaking, removing all the parts and jets, and installing the new kit.